Fluid pbesstjbe brake device



Jan. 8, 1935. Tl H, THOMAS Re. 19,420

FLUID PRESSURE BRAKE DEVICE original Filed Aprvil 9, 1925 3 sheets-sheet 1 #VVE/V701? THOMAS l-LTHOMAS DECEASED MABLE MTI-{CMAS} EXECUTRIX Jah. 8,."1935.

T. H. THOMAS FLUID PRESSURE BRAKE DEVICE Original Filed April 9, 1925 3 Sheets-Sheet 2 .S-COND MN5/v70@ HOMAS H THOMAS DECESEU MABLEMTHOMAQEX ECUTRIX BY Wwf In a A TTORN Y Jan. 8, 1935. T. THOMAS Rev., 19,420l

FLUID PRESSURE BRAKE DEVICE Original Filed April 9, 1923 3 Sheets-Sheet 5 MED. SPEED MAGNET. HlGH SPEED MAGNET.

IDO

TRAlN AT H|GH SPEED RECEIVES A MEDIUM SPEED 1ND|CAT|0N NoTAcKNowLEDcfED) MAIN RES.

SELECTOR VALVE ,o4 DEVICE.

lo CHANGE SPEED VALVE DEVICE.

APP- VALVE. DEVICE.

v. IOS MED. SPEED VALVE DEVICE.

STOP RES.

/NVENTOR THOMA H THOMAS DECEASED MABLE MTHOMAB, EX EC UTRD( BY A TTORN Reissued Jan. 8, 1935 Re.

UNITED STATES PATENT GFFICE FLUID PRESSURE BRAKE DEVICE Thomas H. Thomas, Edgewood, Pa., assigner to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Original No. 1,533,481, dated April 14, 1925, Serial No. 630,686, April 9, 1923. Application for reissue November 19, 1926, Serial No. 149,548

56 Claims. (Cl. 303-18) This invention relates to a uid pressure brake As shown in the drawings, the equipment may application controlling device, and more particucomprise a brake application valve device, the larly as applied to an automatic train speed conoperation of which is controlled by an automatic trol equipment. speed control apparatus (not shown). Said Valve 5 It is a well known fact that long trains can be device may comprise a casing 1 having a piston 5 handled more smoothly by means of a graduated chamber 2 connected to a speed control pipe 57, rather 'than a continuous application .of the through which the fluid pressure in piston chambrakes, since there is danger when a heavy conber 2 is'varied according to the operation of the tinuous brake pipe reduction is made that the speed control apparatus. A piston 3 contained l brakes will be applied at the head end of `the in piston chamber 2 is adapted to operate a slide 10 train suiciently'in advance of those at the rear valve 4, contained in valve chamber 5 which'comend as to cause the slack of the train to run in municates through passage 6 with a source of harshly and thus produce dangerous shocks and fluid under pressure, such as the main reservoir 7. possibly a break-in-two on the recoil. The rec- Associated with the application valve device is l ommended practice for manipulating the brakes an equalizing discharge valve mechanism com- 15 on a long train in order to overcome this difliprising a casing 8 containing a piston 9 having culty, consists in first making an initial light the chamber 10 at one side connected by a pasbrake pipe reduction, such as to insure that all sage 1l With an equalizing reservoir 12 and the the brakes on the train will apply, and then after chamber 13 at the opposite side with the usual moving the brake valve handle to lap position train brake pipe 14. Said piston is adapted to 20 and holding the same there until the brake pipe operate a discharge valve 15 for venting fluid exhaust ceases, to eiect a heavier brake pipe refrom the brakepipe 14 to effect a reduction in duction sufficient to produce the desired applicabrake pipe pressure and thus cause an application of the brakes. tion of the brakes in the well known manner.

The principal object of my invention is to pro- The mechanism for automatically effecting the 25 vide means for accomplishing automatically what split or two application feature of my invention is accomplished by the engineer manipulating the may comprise a casing 16 containing a pilo-t valve brake valve as above stated. mechanism and a hold back Valve mechanism'.

In the accompanying drawings; Fig. 1 is a The pilot valve mechanismA may comprise a holdiagrammatic view, in section, of a brake applilow piston 17 having the piston chamber 18 at 30 cation controlling deviceembodying my inventhe closed end of the piston connected to a pastion and showing the parts in normal release sage 19 which leads to the seat of application position; Fig. 2 a similar View, showing the parts slide valve 4 and which is also connected to a in brake application position, as initially astiming reservoir 20.

sumed; Fig. 3 a sectional view of the pilot valve In the open end of the piston 17 is mounted a 35 mechanism shown in Figs. 1 and 2 and in a posicollapsible piston 21 having a longitudinal slot tion assumed after a period of time; Fig.` 4 a for receiving a pin 22 which is secured to piston sectional View of the pilot and hold back valve 17. Interposed between the closed end of piston mechanism of Figs. 1 and 2, showing the parts in 17 and the collapsible piston 21 is a coil spring position to effect the second reduction in brake 23. The piston 21 carries a valve 24 for con- 40 pipe pressure; and Fig. 5 a diagrammatic View, trolling communication from a chamber 25 to an showing my invention associated with a signal atmospheric vent port 26, which port also comand speed control equipment. municateswith an intermediate chamber 27.

A desirable application of my invention in con- The hold back valve mechanism may comprise 4c nection with an automatic train speed control a hollow piston 28 having a seat` 29 at one end for 45 equipment where the application of the brakes is engaging a seat ring 30. The inner seated area automatically effected through thev operation of of the seat 29 is connected by a passage 31 with a the automatic speed control equipment, indesecond reduction reservoir 32 and the outer seated pendently of the engineer, and in the drawings area is connected by a passage 33 with a flrst I have shown my invention as` applied to an reduction reservoir 34. A spring 35 tends to 50 automaticspeed control equipment of which the maintain the piston 28 seated at the right and application valve device functions and is conmovement of said piston to the left is adapted to trolled identically with the application valve deoperate a valve 36 through engagement with a vice of my prior Patent No. 1,523,462, issued stem 37. The left hand end of piston 28 is flared January 20, 1925.- to form a seating ring 39 which is adapted to en- 55 Cir the brake pipe 14 flows to the chamber 13 of thel equalizing discharge piston 9 and through a passage 42, past a check valve 43, a cavity 44 in slide valve 4, and a passage 45 to the piston chamber 10. From passage 45 uid also flows through passage 11 to the equalizing reservoir 12, charging same to the pressure carried in the brake pipe 14.

The first reduction reservoir 34 4is vented to the atmosphere through passage 46 4and cavity.

47 in slide valve 4 to exhaust port 58. I'he second reduction reservoir 32 is also vented to the atmosphere by Way of passage 31 and past the check valve 51 to the passage 46, through which fluid is vented from the first reduction reservoir, as previously described.

The passage 19 being connected through-cavity 47 in slide valve 4 `with exhaust port 58, the piston chamber 18 of piston 17 and the timing reservoir 20 will be at atmospheric pressure, so that the light coil spring 52, acting on the opposite side of piston 17 will hold said piston to its extreme position at the right, as shown in Fig. 1, ywith the valve 24 held unseated by the operation of the collapsible piston 21. The valve chamber 38 containing the valve 39 being connected to the atmosphere through passage 59, chamber 25, and past the open valve 24 to exhaust port 26 and the opposite side of piston 28 being also at atmospheric pressure, the spring 35 will maintain said piston in tsseated position at the right, as shown in Fig. 1.

When iiuid under pressure is vented from piston chamber 2 of the application valve device through pipe 57, by the operation of the speed control apparatus, the piston 3 will be shifted to application position, as shown in Fig. 2.

In this position, fluid is vented from the equalizing reservoir 12 and the piston chamber 10 of the equalizing discharge valve piston 9 to the first reduction reservoir v34, through passages 11 and 45, port 53 in slide valve 4, said port having a restricted portion 54, and passage 46, to the first reduction reservoir 34. The pressure in the equalizing reservoir l2 expanding intov the first reduction reservoir 34, reduces the equalizing reservoir pressure by a predetermined amount. For example, the volume of the rst reduction reservoir 34 may be such that equalization will cause a reduction of eight pounds in the equalizing reservoir pressure.

The equalizing piston 9 is then shifted by the higher brake pipe pressure acting in chamber 13, so as to unseat the discharge valve 15 and permit the ventingof fluid from the brake pipe 1.4 so as to effect an application of the brakes. kWhen the brake pipe pressure has been reduced to a degree slightly less than the reduction in equalizing reservoir pressure, the piston 9 will be operated to move the valve 15 toits seat, thus preventing the further discharge of fluid from the brake pipe.

Fluid thus vented from the brake pipe is not vented directly to the atmosphere as usual, but. is vented to the timing reservoir 20 and the piston chamber 18 of the pilot valve mechanism by Way of passage 55, a port 56 in slide valve 4, leading to cavity 47 and thence through passage 19 to the timing reservoir 20.

As fluid discharged from the brake pipe 14 flows into the piston chamber 18 at a greater rate than it can escape through the restricted ports 48 and 49, the pressure Will be built up in piston chamber 18 so as to 'move the piston 17 to the left, compressing the light spring 52,and causing the valve 24 to seat, as shown in Fig. 2. In this position, further movement of piston 17 to the left is opposed'by the heavier coil spring 23, but the further rapid building up` of pressure in piston chamber 18 and in the timing reservoir 20 by 110W from the brake pipe causes a further movement of pis- `tori 17 to the left.`

Upon said further movement to the left, the piston 17 moves relatively to the piston 2l owing to the collapsible character of piston 21, so that communication is established from piston chamber 18, past a reduced section of piston 17 to chamber 27, as shown in Fig. 3. The chamber 27 being open to exhaust port 26, a rapid venting of fluid from the timing reservoir 20 and the piston chamber 18 takes place so long as the discharge valve 15 remains open. When the discharge valve 15 closes after the predetermined reduction in brake pipe pressure has been completed, the pressure in piston chamber 18 and in timing reservoir 20 falls rapidly, permitting the reservoir spring 23 to move the piston 17 to the position shown in Fig. 2 in Which the exhaust port piston 17 to chamber 27 is eut off.

The further reduction in pressure in piston .chamber 18 and in timing reservoir 20 takes place at a slower rate by escape through the restricted ports 48 and 49. to the exhaust port 26 and when the pressure has been reduced to a degree slightly less-than the valueof the light spring 52, the piston 17 will be shifted to the right, so as to cause the collapsible piston 21 to unseat the valve 24, as shown in Fig. 1.,

During the above operation, the fluid pressure equalized into the first reduction reservoir 34 is supplied through passage 33 to the outer seated area of piston 28 and from said area through passage to valve chamber 38 and consequently when the valve 24 is opened by the operation of the piston 17, iiuid is vented from valve chamber 38 through passage 59 to chamber 25 and thence past the open valve 24 to exhaust port 26. The uid pressure acting on the outer seated area of piston 28 then operates to shift said piston to the left, as shown in Fig. 4, so `that passage 33 is connected to passage` 31. Fluid under pressure in the equalizing reservoir 12 and in the first reduction reservoir 34 Willthen, equalize into the second reductinreservoir 32and thus a second reduction in pressure in chamber 10 of the equalizing discharge valve mechanism is effected and thereby the valve 15 is operated to effect a second predetermined reduction in brake pipe pressure, corresponding with the combined volumes of the first andsecond reduction reservoirs.

In the open position of piston 28, the seat ring 39 seats, so as togcut off communication from valve chamber 38 to passage 59 and exhaust port 26, thus preventing a reduction of pressure in the reduction reservoirs by flow' through the passage 60.

In this movement, the piston 28 lengages the stem 37 of valve 36 and operates to lift said valve from its seat,I so that although the piston 17 is operated to close the valve 24 during the second reduction in brake pipe pressure, the area of piston 28 which is seated by the seat ring 39 will be maintained at atmospheric pressure by the venting of fluidfrom said seated area past the valve 36 to the atmospheric exhaust port 61, to provide against possible leakage of fluid under pressure from chamber 38 around the seat ring 39 to the inner seated area of thefpiston 28.

When the application piston 3 moves back to release position in releasing the brakes, the reduction reservoirs 32 and 34 are connected through cavity 47 in slidevalve 4 with exhaust port 58, so that fluid under pressure in said reservoir is vented to the atmosphere, and opposite sides of the hold back piston 28 being at atmospheric pressure, the spring 35 returns said piston to its normal position, as shown in Fig. 1.

In the operation of the above described apparatus, the volume of the timing reservoir 20 determines the time elapsing between the first reduction in b-rake pipe pressure and the second reduction and in some instances it will not be necessary to provide a timing reservoir, in which case, the apparatus operates to effect the second reduction in brake pipe pressuresubstantially upon completion of the venting of fluid from the brake pipe in effecting the first reduction in brake pipe pressure.

In Fig. 5 is illustrated the application of the invention to the signal and speed control equipment disclosed in my prior Patent No. 1,523,462.

Fig. 5 is identical with Fig. 5 of the patent except that the application valve device of the present invention is substituted for the application valve device of the patent,

Briefly described, when a train running at high speed receives a medium speed signal indication from the track circuits, the high speed magnet 100 is deenergized thereby, While the medium speed magnet 101 is energized.

'I'he deenergization of the high speed magnet 100 causes fluid under pressure to be vented from the piston 102 of the change speed Valve device by way of passage 103, cavity 104 in slide valve 105 of the selector valve device, passage 106 and past the valve 107 to the atmosphere.

'I'he change speed valve device is then shifted to the position shown, in which passage 57 is connected to the speed controlled valve 108 by way of passage 57, cavity 109 in slide valve 110 of the change speed valve device, passage 111, cavity 112 of the acknowledging valve device 113, and passage 114.

If the speed of the train exceeds the low speed limit, the valve 108 will be unseated by operation of the train speed controlled governor 115, so that the piston chamber of the application piston 3 'is vented to the atmosphere and thereby the ap plication valve device is shifted to application position, so that the brakes are applied as herein- 'before described, by rst effecting a reduction in brake pipe pressure by venting to the rst reduction reservoir and then a second reduction in brake pipe pressure by venting to the second reduction reservoir.

While the apparatus has been described as operating in connection with an automatic train speed control equipment, it will be evident that the apparatus may be employed in connection with the usual brake pipe equipment,v in which ycase the usual engineers brake valve is provided with ports and cavities corresponding With those in the slide valve 4, so that when the brake valve device is turned by the engineer `to brake application position, lthe apparatus will operate the same as when the slide valve 4 is moved by piston '3 to brake applicationposition.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:-

1. In a fluid pressure brake, the combination with a brake pipe, of means for effecting a predetermined reduction in brake pipe pressure and means operated automatically upon completion of said predetermined reduction in brake pipe pressure for effecting a second reduction in brake pipe pressure.

2. In a fluid pressure brake, the combination with a brake pipe, of means for automatically effecting a predetermined reduction in brake pipe pressure and then a second reduction in brake pipe pressure upon the completion of the rst reduction in brake pipe pressure.

3. In a fluid pressure brake, the combination with a brake pipe, of means for effecting apredetermined reduction in brake pipe pressure and means controlled by fluid vented from the brake pipe for effecting a second reduction in brake pipe pressure. f

4. In a fluid pressure brake, the combination with a brake pipe, of means for effecting a predetermined reduction in brake pipe pressure, additional means for effecting a second reduction in brake pipe pressure, and means ontrolled'by fluid vented from the brake pipe in making said predetermined reduction in'brake pipe pressure for holding back the operation of said additional means.

5. In a fluid pressure brake, the combination with a'brake pipe, of means for effecting a predetermined reduction in brake pipe pressure, additional means for effecting a second reduction in brake pipe pressure, and means operated by fluid vented from the brake pipe in making said predetermined reduction in brake pipe pressure for preventing the operation of said additional means.

6. In a fluid pressure brake, the combination With a brake pipe, of means for effecting a predetermined reduction in brake pipe pressure, additional means for effecting a further reduction in brake pipe pressure, and means for delaying the operation of said additional means. v

7. In a fluid pressure brake, the combination with a brake pipe, of means for effecting a predetermined reduction in brake pipe pressure, yadditional means for effecting a further reduction in brake pipe pressure, and means for delaying the operation of said additional means while the predetermined reduction in brake pipe pressure is being effected.

8. In a fluid pressure brake, the combination with a brake pipe, of a valve mechanism for venting iiuid from the brake pipe, means for effecting the operation of said valve mechanism to produce a predetermined reduction in brake pipe pressure, and means subject to the `pressure of fluid vented from the brake pipe for controlling the operation of said valve mechanism to. effect a second reduction in brake pipe pressure.

9. In a fluid pressure brake, the combination with a brake pipe, of an equalizing reservoir, a valve mechanism subject to the opposing pressures of the equalizing reservoir and the brake pipe for venting fluid from the brake pipe, a first and a second reduction reservoir, and means for first connecting the first reduction reservoir to said equalizing reservoir and then the second reduction reservoir.

10. In a fiuid pressure brake, the combination with a brake pipe, of an equalizing reservoir normally charged with fluid under pressure,.a

valve mechanism subject. to the opposing pressures of said reservoir and the brake pipe for controlling the venting of fluid from the brake ma first reduction reservoir, a second reduction reservoir, both normally at atmosphericpressure, and .means for first connecting the first reduction reservoir to said equalizing reservoir and then to the second reduction reservoir.

11. In a fluid pressure brake, the combination with a brake pipe, of a valve mechanism for venting fluid from the brake pipe to effect a reduction in brake pipe pressure, valve means for effecting the operation of said valve mechanism, a valve device subject to the pressure of fluid vented from the brake pipe by operation of said valve mechanism for controlling the operation of said valve means, and a restricted communication through which fluid vented from the brake pipe to said valve device is vented to the atmosphere.

12. In a fluid pressure brake, the combination with a brake pipe, of a valve mechanism for venting fluid from the brake pipe, means for effecting the operation of said valve mechanism to produce a predetermined reduction in brake pipe pressure, valve means foreffecting the operation of said valve mechanismvto produce a second reduction inbrake pipe` pressure, and a valve device subject to the pressure of fluid vented from the brake pipe in effecting said predetermined reduction in brake pipe pressure and operative upon a predetermined reduction in uid pressure by escape through a restricted port for effecting the operation of said valve` means..

13. In a uid pressure brake, the combination with a brake pipe, of a valve mechanism for venting fluid from the brake pipe to effect a reduction in brake pipepressure, valve'means for effecting the operation of said valve mechanism, and a valve device for effecting the operation ofsad valve means and operated by the flow of fluid vented from the brake pipe by operation of said valve lmechanism for preventing the operation of` said vvalve means.

14. In a fluid pressure brake, the combination with a brake pipe, of an equalizing reservoir, a valve mechanism subject to the opposing pressures of theY brake pipe and the equalizing reservoir for controllingr the venting of fluid from the brake pipe, a reduction reservoir, an application valve device=operative to connect said reduction reservoir with the equalizing reservoir, a second reduction reservoir, valve means operative to connect said second reduction reservoir with the equalizing reservoir, and means for delaying the operation of said valve means.

15. In a fiuid pressure brake, the combination with a brake pipe, of an equalizing` reservoir, a

valve mechanism subject to the opposing'pressures vof the brake pipe and the equalizing reservoir for controlling the venting of fluid from the brake pipe, a reduction reservoir, a train speed controlled application valve device operative to connect said reduction reservoir with the equalizing reservoir, a second reduction reservoir, valve means `operative to connect said second reduction reservoirwith the equalizing reservoir, and means for delayingthe operation of said valve means.

16. In a uid pressure brake, the combination with a brake pipe, of a valve mechanism for venting fluid from the brake pipe to effect a reduction in brake pipe pressure, valve means operative to effect the operation of said valve mechanism, a timing reservoir, a valve ldevice subject to the pressure oi' Iiuid vented from the brake pipe to said timing reservoir by operation of said valve mechanism for controlling the operation of said valve means.

1'7. In a nuid pressure brake, the combination with a brake pipe, of a valve mechanism for venting fluid from the brake pipe to effect a reduction in brake pipe pressure, valve means operative to effect the operation of said valve mechanism, a valve device subject to the pressure of fluid vented from the brake kpipe by operation of said-valve mechanism for controlling the operation of said valve means, yand an application valve device for controlling communication through which uid vented from the brake pipe is supplied to` said valve device. v

18. In a fluid pressurebrake, the combination with a brake pipe, of a valve mechanism for venting iiuid from the brake pipe to effect a; reduction in brakepipe pressure, and a valve device for controlling communication through which uid is vented from the brake pipe by operation of said valve mechanism and operable upon the cessation of venting of fluid from the brake pipe for effecting a second operation of said valve mechanism to produce a second reduction in brake pipe pressure.

19. In an automatic train control apparatus, the combination with a brake pipe, of means for automatically effecting al reduction in brake pipe pressure in two stages', a valve device having positions for cutting said means into and out of action, and means operating upon a change in the signal indication for controlling the operation of said valve device. l

20. In an automatic train control apparatus, the combination with a brake pipe, of means for automatically effecting a reduction in brake pipe pressure in two stages, and mechanism controlled in accordance with the speed of the. train for rendering said means veffective or ineffective.

21. In an automatic train control apparatus, the combination with a brake pipe, of means for automatically effecting a reduction in brake pipe pressure in two stages, and mechanism having a position for rendering said means ineffective and movable upon a change in the speed of the train to ak position for rendering said `means effective.

22. In an automatic train control apparatus, the combination with a brake pipe, of means for automatically effecting a reduction in brake pipe pressure in two stages, mechanism for cutting said means into and out of operation, a speed governor operated according to the speed of the train, and means controlled by said speed governor for controlling they operation of said mechanism. Y

f. 23. In a train contro'l apparatuathe combination with a brake pipe, of means for effecting a reduction in brake pipe pressure in two stages and a valve device operative to cut said means out of action. l

24. In a fluid pressure brake,:the combination with a brake pipe, of means for effecting a reduction in brake pipe pressure in two-steps and a valve mechanism' operative to cut said means out of action.

25. Brake applyingmechanism for automatic train control systems comprising, means associated with the usual air brake system for effecting a two stage brake applicationwhich if initiated will rst reduce the brake pipe pressure to a predetermined extent vsufficient to bunch the slack between successivecars of a train and then a predetermined time thereafter suflicient to allow such bunching of cars will cause a further and predeterinned reduction in the brake pipe pressure, and means for initiating said means.

26. Brake applying mechanism for automatic train control systems comprising, means associated with the usual air-brake system which will cause a predetermined pressure reduction in the brake pipe when initiated and then after a predetermined lapse of time depending upon the speed of the train will cause a further predetermined reduction, and means for initiating said means.

27.\In an automatic train control system, the combination with the usual air-brake system, of a pressure reservoir and a reduction reservoir, an application valve for normally connecting said pressure reservoir to the brake pipe and said reduction reservoir to atmosphere, said valve if operated connecting said reservoirs to each other to cause a pressure reduction in said pressure reservoir, means for venting the brake pipe when the pressure therein exceeds that of the pressure res-- ervoir, and means for causing a further predetermined pressure reduction in said pressure reservoir after a predetermined lapse lof time following the operation of said application Valve.

28. Mechanism for automatically applying the brakes for train control purposes on vehicles equipped with the usual air-brake system comprising, in combination with the usual brake pipe, a pressure reservoir, a reduction reservoir, an application valve normally connecting the reduction reservoir to atmosphere and the pressure reservoir to the brake pipe, said application valve being operable to disconnect said normal connections and connect said reservoirs together,

' means for automatically causing a reduction in brake pipe pressure to accord with that in the pressure reservoir after the application valve has operated, a second reduction reservoir normally at atmospheric pressure, a secondary application valve for further reducing the pressure in the pressure reservoir by connecting it to the second reduction reserv-oir, and means for automatically operating said secondary application valve after the lapse of a predetermined interval of time following the operation of the first mentioned application valve.

29. Mechanislnfor automatically applying the brakes for train control purposes on railway vehicles equipped withv the usual automatic air-brake system comprising, means operable to vent the brake pipe pressure to a predetermined extent in successive stages, and means having its operation dependent upon the lapse of time and. automatically controlled simultaneously with said rst mentioned means for determining the time intervening between said successive stages of reduction. f

30. Mechanism for automatically applying the brakes of railway vehicles equipped with the usual automatic air-brake system comprising, pressure responsive means for venting the brake pipe of the air-brake system down to a predetermined pressure corresponding to that governing said means, and automatic means for varying the controlling pressure for said means in two successive stages with an intervening time interval.

31. Mechanism for automatically applying the brakes of railway vehicles equipped with the usual automatic air-brake system comprising, a pressure reservoir, a pressure operated valve for venting the brake pipe of the air-brake system down to apressure equal to that then existing in said pressure reservoir, automatic means operable to reduce the pressure in said pressure reservoir to a predetermined ,value in two successive stages with an intervening time interval.

32." In a system of automatic control for the air brakes .of vehicles 'for train control purposes, the combination with the usual brake pipe, a pressure operated.V valve for venting the brake pipe, a reservoir supplying pressure to said valve, control means operable to reduce pressure in said reservoir in two successive stages, and timing means set into operation .concurrently with the initiation of the operation of said control means for determining the interval of time between said stages. ,"1

33. In a system of automatic control for the air brakes. of vehicles for train control purposesLthe combina-tion with the usual brakev pipe, a pressure reservoir, a valvel venting the brake pipe to atmosphere until its pressure corresponds with that then existing in saidreservoir, a reduction reservoir normally at atmospheric pressure, means operable to connect the pressure reservoir to the reduction reservoir and thereby make a predetermined reduction in pressure in the pressure reservoir dependent upon the relative volumes of said reservoirs, a second reduction reservoir, and timing,r means automatically set into operation upon equalization of the pressures in the first reduction reservoir and the pressure reservoir for connecting the latter to the second reduction reservoir after the lapse of an interval of time.

34. Brake applying mechanism for automatic train control systems comprising, meansoperable to reduce the brake pipe pressure in the usual airbrake system to a kpredetermined fractional part of its original value when operated, and other automatic means for further reducing the brake pipe pressure to a predetermined fractional part of the then existing pressure, said last mentioned means being operated a predetermined time after said-first mentioned means has been operated.

. 35. In air-brake controlling apparatus of -the character described, the combination with a brake pipe, of automatic means venting the brake pipe to varying extents in succession with an intervening time interval suicient to allow the slack between the cars of a train to be taken up.

36. In air-brakecontrolling apparatus of the character described, the combination with a brake pipe, of automatic means producing two successive reductions in brake pipe pressure. of different values and spaced apart a period of time sulicient, to allow the slack between the cars of a train to be taken up.

37. In an automatic pressure brake apparatus, a brake pipe, a reservoir, a diierential valve device subject to opposing pressures from said brake pipe and reservoirandoperable to permit escape of fluid from the brake pipe when the brake pipe pressure is greater than the reservoir pressure, and automatic means for obtaining periodic successive reductions in pressure in said reservoir.

38. In an auto-matic pneumatic brake apparatus, a brake pipe, a reservoir, a diflerentialvalve device subject to opposing pressuresfrom said brake pipe and reservoir and operable to permit escape of fluid from the brake pipe when the brake pipe pressure is greater than the reservoir pressure, a plurality of expansion chambers, and automatic means for connecting said reservoir with the expansion chambers in succession to obtain periodic successive reductions in reservoir pressure. f

39. In an automaticv pneumatic brake apparatus, a brake pi'pe,'*a reservoir, a differential valve'l devies subie@ t0 opposing pressures from .said brake pipe and reservoir .and operable to Permit cape of iluid :from the brake'pipe when the brake pipe pressure is greater than the reservoir pressure, and automatic means for obtaining, in one position, periodic successiveV reductions in said reservoir pressure, and, ranother position, to connect the train pipe and reservoir.

' 40.` In an automatic pneumatic brake apparatus, a brake pipe, a reservoir, a dierential valve device subject to opposing pressures from said brake pipe and reservoir and operable to permit escape of fluid from the 'brake pipe when the brake pipe pressure is greater than the reservoir pressure, a plurality of expansion chambers, and

- automatic means operable, in one position, for

connecting said reservoir in succession with said chambers for obtaining periodic successive reductions `in reservoir pressure, and operable, in another position, for connecting the brake pipe and reservoirr and opening -said chambers to the atmosphere.

v41. In an automatic pneumatic brake apparatus, 'a brake pipe, areservoir, a differential valve device subject to opposing` pressures from said' f brake pipe and reservoir and operable to permit the escape of .pressure fluid from the brake pipe when the brake pipe pressure is greater than the reservoir pressure, an expansionbhamber, and

automatic means for connectingl said reservoirV With said chamber and operable, after said chamber isfllled with fluid from the reservoir, to permit further escape of fluid from the reservoir.

- .42. In anfautomatic pneumatic brake appara-Y v tus, a brake pipe, a reservoina differential valve device subject to opposing pressures from said reservoirpressure, an expansion chamber, and' automatic means for connecting said reservoir with saidchamber and operable'after'said'chamber islled with fluid from the reservoir, to permit further escape of Viluid from the reservoir, said automatic means being arranged', when restored,

to prevent escape of fluid from the reservoirand to connect the brake pipe and reservoir.

43.v In' an automatic pneumatic brakev apparatus, a brake pipe, a reservoir, adifl'erential valve device subject to opposing pressures from said brake pipe and reservoir and *operable to permit escape of uid from therbrakepipe when the brake pipe. pressure is greater than the reservoir pressure, an expansion chamber, automatic means for connecting said reservoir with said chamber, and automatic means operableI after' an interval of time after said chamber islled with' pressure iiuid from the reservoir, for permittingv further.

escape of pressure iiuid from the reservoir.

44. In an automatic pneumatic brake apparatus, a brake pipe, a reservoir, a differential valve device subject to opposing pressures from said brake pipe and reservoir and operable to permit escape of pressure uuid from the brake pipe when the brake pipe pressure isv greater than the reservoir pressure. a pluralityy of expansion chambers,

45. In an automatic pneumatic brake apparatus, a brake pipe, a. reservoir, a.. difrerential valve device subies# te @Deinem-essersi@ Sau brake pipe and reservoir and operable topermt escape of pressure fluid from the brake pipe when the brake pipe pressure is greater than the reservoir'pressure, a plurality of expansion chambers, automatic'means for connecting the reservoir and one expansion chamber, andV automatic means operable, after an interval of time after said expansion chamber is iilled with iiuid from they reservoir, for connecting the reservoir and other expansion chamber, said automatic means being arranged, when restored, to connect the reservoir and brake pipe and to: connect said expansion chambers with the atmosphere- 46. In,y an automatic pneumatic brake apparatus, a brake pipe, a" reservoir, a diii'erential valve device subject to opposing pressures from said brake pipe and reservoir and operable to permit escape of pressure Huid from the brake pipe when the brake pipeY pressurev is greater thanthe reser- Voir pressure, and automatic means operable for obtaining a predetermined reduction in pressure insaidreservoir, and operable, after an interval agiter such reduction in reservoir pressure, to obtain a further reductionin reservoir pressure.

47. In an automaticpneumatic brake apparatus', a 'brale pipe, a reservoir, a differential Valve device subject to opposing pressures from said brake pipe and reservoir and operable to permit escape of pressure fluid from the brake pipe when the brake 'pipe pressure is greater than the reservoir pressure, a plurality of expansion chambers, automatic valve means for normally connecting the reservoir and brake pipe and operable for disconnecting them and connecting the reservoir and one expansion chamber, and valve means brought into'operation when the chamber is lled with fluid from the reservoir and operable for connecting the reservoir' and the other expansion chamber.

48. In an automatic pneumatic brakeapparatus, a brake pipe, means'operable by brake pipe pressure for reducing the brake pipe pressure, fiuidfpressure means controlling the aforesaid means in opposition to brake pipe pressure to prevent reduction in brake pipe pressure, and means for. obtaining periodic successive reductions in pressure in the second named means so as toobtain periodic successive reduction in brake pipe pressure.

'49..In an automatic pneumatic brake appara--A tus, a brake pipe, means operable by brake pipe` pressure. for obtaining a. reduction in such pressure, fluid pressure means controllingsaid means in opposition tov brake pipe pressure toV preventy reduction. in brake pipe pressure, a plurality of expansion chambers, andfautomatic means for connecting the second-named means with said expansion chambers in succession to obtain periodic. successive reductions inthe pressure. op- Posing the brake pipe pressure, so as to obtain periodic successive. reductions in brake pipe pres- SLlIE.` 50.A In an automatic brakeY apparatus, a brake; pipe, means operable by brake pipe pressure for they reduction. of` such pressure, uid pressure means controlling saidr means and opposing brake pipe pressure to prevent reduction in brake pipe Pressure, an expansion chamber, automatic means for connectingV the second-named means and said expansion chamber for al predetermined reduction inthe pressure. opposing brake pipe pressure so as to obtain apredetermined reduction, in pipepressure, and ,automatic .means Operable. after: au interval;l Off time ,fcillowlns the Wlierressme fluter;

for permitting further escape of pressure fluid from the second named means to obtain a further reduction in brake pipe pressure.

51. In an automatic pneumatic brake apparatus, a brake pipe, means operable by brake pipe pressure for the reduction in said pressure, fluid pressure means controlling said means and opposing brake pipe pressure to prevent reduction in brake pipe pressure, signal and speed control means controlling the second named means and operable underI a predetermined signal impulse and above a predetermined speed for obtaining a limited reduction in pressure in the second named means for obtaining a corresponding reduction in brake pipe pressure, and automatic means operable, after an interval of time follow-- ing such pressure reduction, for permitting further escape of pressure fluid to obtain a further reduction in brake pipe pressure.

52. In an automatic pneumatic brake apparatus, a brake pipe, automatic means controlled by a signal impulse and Vehicle speed and operable upon receipt of a predetermined signal impulse and above a predetermined vehicle speed for obtaining a limited reduction in brake pipe pressure, and automatic means operable for obtaining a further reduction in brake pipe pressure after an interval following the aforesaid reduction in brake pipe pressure.

53. In a fluid pressure brake, the combination with a brake pipe, of two reduction reservoirs, means operated upon a venting of fluid under pressure into either reservoir for effecting a reduction in brake pipe pressure, one reservoir being connected for venting purposes only after the venting of fluid from the brake pipe due to venting of iuid under pressure to the other reservoir has ceased.

54. In a duid pressure brake, the combination with a brake pipe, of a first reduction reservoir, a second reduction reservoir, and means for first venting uid under pressure to the rst reservoir to effect a reduction in brake pipe pressure and then to the second reduction reservoir to effect a second reduction in brake pipe pressure, said reservoirs being connected the/ one to the other only after the nrst reduction in brake pipe pressure has been completed.

55. In a fluid pressure brake, the combination with a brake pipe, of a first reduction reservoir, a Isecond reduction reservoir initially out of cornmunication with the rst reservoir, and means for .first venting fluid under pressure to the lrst reservoir to effect a reduction in brake pipe p-ressure and then only after the rst reduction ceases to the second reduction reservoir to effect a second reduction in brake pipe pressure.

56, In a fiuid pressure brake, the combination with a brake pipe, of a first reduction reservoir, a second reduction reservoir, a valve device having a position in which the first reduction reservoir is connected to the second reduction reservoir, and valve means having one position for connecting one side of said valve device to the atmosphere and another position in which uid under pressure is supplied directly to said valve device.

THOMAS H. THOMAS. 

